Outline

Objective

To determine the exact size of ruptured and unruptured aneurysms using the newly developed three dimensional-rotational angiography (3D-RA).

Methods

N=118 consecutive patients with n=155 saccular intracranial aneurysms were prospectively included in the study and received 3D-RA reconstructions for measurement of maximal height and width of the aneurysmal sac. Statistical evaluation compared values for ruptured (n=83) and unruptured (n=72) aneurysms.

Results

Mean (median) height of UIAs was 5.7 (4.4) mm, mean width 5.7 (4.7) mm. Mean height of RIAs was 6.7 (5.6) mm, mean width 6.1 (5.0) mm. There was only a small difference in height and width between RIAs and UIAs of 1.0 mm and 0.4 mm which was statistically not significant (p=0.7 for height and p=0.9 for width). The majority of RIAs, 68 out of 83 (81.9%) and 49 out of 83 (59%) were smaller than 10 mm and 7 mm; likewise 59 out of 72 (81.9%) and 49 out of 72 (68.1%) UIAs were smaller than 10 mm and 7 mm. The difference in frequency of small (<10/7 mm) aneurysms between UIAs and RIAs was not significant (p=1.0/p=0.32). The size category of most RIAs was 4-6 mm in height and 2-4 mm in width. A critical threshold-size for aneurysm rupture could not be identified.

Conclusions

3D-RA data demonstrate that knowing the method of aneurysm-size measurement is important for interpretation of results. The technical advances and better visualisation of aneurysm- and parent vessel-morphology utilizing 3D-RA allows exact measurement of intracranial aneurysms, which may be much smaller than previously thought.